1. Field of the Invention
The present invention relates to a color image processing method for obtaining primary color signals to form a color image from an input color image signal.
2. Related background art
FIG. 1 is a block diagram of an ink jet printer for forming a color image from a video signal, wherein a conventional signal processing technique is specifically shown. The description of the operation associated with FIG. 1 will be given hereinunder. Input signals R, G and B are converted into digital signals by an A/D converter 11 and thereafter, the converted signals are respectively input to gamma (.gamma.) converters 12R, 12G and 12B which perform gradation and complementary color conversions, whereat the digital color signals R, G and B are converted into gradation-converted complementary color signals C, M and Y. The signals C, M and Y are subjected to a masking process by means of a masking ROM 14 for eliminating impurity components of ink (inhomogeneous color components) and thereafter become C', M' and Y', which are signals representative of the optical densities of ink (OD values). The signals C', M' and Y' are respectively converted by an OD/voltage converter 16 into analog drive voltages necessary for driving heads 18C, 18M and 18Y and obtaining the OD values. The analog drive voltages are respectively applied to the corresponding heads to discharge ink droplets 20C, 20M and 20Y therefrom to form a desired color image on a recording medium (not shown).
According to the related art, the gamma (.gamma.) converter 12 is required to be provided for each color signal, thus resulting in a large circuit construction. Furthermore, as to the masking ROM made of masking conversion tables, it is difficult to reduce the capacity of the ROM because the capacity reduction affects the color reproduction fidelity.